This Is How Much SPF You Need To Use


The sun protection factor (SPF), is a measure of the amount of Ultraviolet B radiation (UVB) protection. The sun emits both UVA & UVB rays. UVA causes tanning through the genetic damage caused which results in the skin darkening to try and protect itself. UVA accounts for 95% of the radiation reaching the earth and can penetrate both cloud cover and windows. Blue light is also a form of this kind of radiation. UVB damages the outer layers of the skin, also causing tanning, sunburn, and blistering. SPF is connected to UVB, the number is based on time you can spend in the sun before the sun reaches the skin. For example, SPF 30 provides 30 times the protection of no sunscreen (If that number were 10mins, you would get 300mins with SPF 30). Typically, car, home, and office block windows block most UVB rays. But only a small portion of UVA rays which means even in doors you require protection. Although some types of tinted windows help block more UVA rays it is still worth investing in a good SPF.

SPFs are rated on a scale of 2 to 50+ which is based on the level of protection they offer. The higher the SPF factor, the stronger the form of UVB protection. For UVA you need to look at the star rating measures. On UK sunscreens you should see a star rating of up to 5 stars, the higher the star rating, the better. Also, on European packaging you’ll find the letters “UVA” inside a circle. This is to tell you that the UVA protection is at least a third of the SPF value and meets EU recommendations.

If you are looking for one which protects against both UVA & UVB then these may be found under protection referred to as broad spectrum.

It is worth noting that the stated SPF protection is based on the correct product volume being applied. It is advised that you should use 2mg per cm2. Based on this, if your face was 0.47 cm2 then you should look to apply just under 0.1ml of product to your face. Although this is not a lot most people unfortunately do not apply enough protection. If there is not enough applied, then the displayed protection is reduced. This is generally why it is advised to use the highest SPF possible.

If you are looking to spend a prolonged amount of time in the sun, then you should be making 2 applications before leaving. This should be 30 minutes before you leave followed by a second application just before you head out. In terms of factor, SPF 30 is the recommended minimum. This blocks 97% of the suns UVB rays (no sunscreen can block 100%). After application you should apply every two hours. A consideration is that you may be at risk rubbing it off with a towel after jumping in the pool even if it states it’s water resistant.

With a selection of sunscreens, it’s not always easy to identify which is best for you. Options include lotions, creams, gels, ointments, wax sticks, and sprays. Generally:   

  • Creams for dry skin
  • Gels for hairy areas (scalp)
  • Sticks on delicate areas (eyes)
  • Sprays are great for time saving  

Some sunscreen products are in combination with cosmetic products like moisturisers and foundations. These still need to be reapplied to achieve the best sun protection. Also, most won’t apply the correct amount of these more so because they require less of the combined product. 

Regardless of which sunscreen you choose, be sure to apply it generously to achieve the UV protection indicated on the product label

There are some skin types which are more susceptible to get skin damage than others. However, no one is immune, and everyone should be wearing some protection when they intend to spend time in the sun.

Of course we all want to get the right levels of Vitamin D and sunlight is the best source of this.



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London based beauty & lifestyle blogger

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